It has been known to use in a cement plant a clinker cooler by which hot cement clinker formed by burning or firing is cooled by air down to a predetermined temperature while it is conveyed through a predetermined distance.
In this kind of clinker cooler, cement clinker fallen from a rotary kiln is received on grates which are moved to convey the cement clinker to a discharge port. Cooling air in a compartment is jetted through the grates to the cement clinker so that the cement clinker is cooled while being conveyed. Cement clinker is classified due to the rotation of the rotary kiln and graded in grain size on the grates in the direction perpendicular to the grate moving direction. Namely, the thickness and grain size of the cement clinker layer on the grate are unevenly distributed in the widthwise direction. Further, the thickness of the cement clinker layer is unevenly distributed also in the cement clinker flowing direction. This makes the cooling air hard to flow locally, that is, the flow resistance to air is increased locally, resulting in a problem that the cooling of the cement clinker cannot be performed sufficiently.
To solve the above problem, according to a clinker cooler disclosed in Japanese Patent Examined Publication No. 3-21496, each of the fixed grates is equipped with an exclusive air chamber and the quantity of cooling air to be jetted is controlled by varying the pressure of cooling air in the air chamber and the temperature of the grate. However, since all the air chambers communicate with a single fan, complex operation of control valves becomes a necessity in order to maintain the pressure in every air chamber properly.
Further, the capacity of the fan must be selected in conformity with the highest flow resistance to air. This causes the power consumption to increase.